This one is annoying me, and I'm wondering if there's anything I overlooked.

After I got the new Sony laptop, I wiped my old one to get it ready for sale. I used the recovery CDs to put the original OS on. That was fine. Put windows updates on. Fine. Friend needed a new laptop as hers was dying, so I offered mine.

Before I passed it over, I thought I'd update the drivers to latest version too. BSOD on installing the wifi. After that happened, it would BSOD randomly in windows, wifi or not.

Bad driver perhaps? I restored the original image again. Did driver updates other than the wifi. Still BSOD. Argh!

Fine, no driver updates then. Re-restored image. Only put on windows updates. After XP SP2 installed... guess what? BSOD. This one I remember was some logon service not working. Can't even get into safe mode.

Fine, not even windows updates then. Just restore original image... BSOD on 1st boot! It would boot after that, but of course confidence is low on stability.

Ok, diagnostic time. memtest86+ 4.x wouldn't start correctly. Reverting to version 2.x did run, and it did one pass without any errors.

Boot into windows. Ran LinX for a while, no errors, consistent results.

No hardware has changed since I was using it myself. Right now, I have no idea on possible causes other than what I've eliminated above.

My next guesses are a transient disk issue, or possibly a CD drive issue. Would the recovery system detect an error on the media? But the crashes seem too random for that, unless it was a random read fault.

I haven't looked in the bios, as being a laptop, there isn't anything in the bios to fiddle with. But I will double check anyway.

I can't do a clean install of XP since I don't have install media, just the recovery CDs that came with the laptop in the first place. On that note, I was thinking of putting Win7 on it. Wont activate, but will be interesting as diagnostic.

Depends on where you got it from, but I'd have to suspect that is a false positive. It's popular as a stability test when system overclocking, but equally works on stock systems if you want to check it. Linpack based workload seems more effective at provoking crashes than the old fave prime95.

If the laptop is able to boot via a memory stick and if it's possible to put the recovery cd on a memory stick as well I would try that.

Also, do you have a spare 2.5" HDD around? A completely clean install skipping all recovery might be worth a shot. (Testing with a Linux distro you are familiar with) At least if this works and does not crash you would be sure that the rest of the hw is in seemingly perfect working order.

Since it's a laptop I would also be a bit afraid of PCB errors, sounds a bit far fetched considering what started your problems, but I have had my fair share of weird RAM issues because of this which seemingly comes out of nowhere and they have a habit of evading test programs as well.

Lastly, if one ever recorded how many hours strange hardware and software malfunctions took to troubleshot it would be a scary number.

I never posted the solution to this did I? The source of the crash has been found: it was the wifi module. I noticed the laptop only crashed when wifi was on regardless if it was used or not. So I physically removed the module and it hasn't crashed since. Of course, a laptop without wifi these days isn't so hot... I did try cleaning the contacts of the module and putting it back in, but it just crashed again. Can only assume it has failed with age.